Earth Friendly: Keep your reusable bags clean

June 29, 2010 at 1:29 a.m.Updated June 30, 2010 at 1:30 a.m.

By Meridith Byrd

Last week, I became aware of a study that found bacteria in reusable grocery bags. Funded by the American Chemistry Council, which is an organization that represents manufacturers of plastics, and conducted by the University of Arizona, the study involved collecting reusable grocery bags from people in Tucson, Ariz., Los Angeles and the San Francisco Bay area.

Bacteria were found in slightly more than half of the bags, and 12 percent were found to harbor Escherichia coli. According to the U.S. Centers for Disease Control, E. coli are a very large group of mostly harmless bacteria, though there are some that can cause illness.

The study did not investigate whether the bags that did contain bacteria harbored concentrations high enough to sicken consumers, though co-author Dr. Charles Gerba recommends that people be vigilant about preventing cross-contamination of food and keeping reusable bags clean.

Cross-contamination can occur when juices from raw meat, for example from leaking packages, come into contact with the bags. The juices contain bacteria that can remain on the bag and contaminate future food purchases.

It is not necessary to wash your bags after each use. However, to prevent cross-contamination, shoppers are encouraged to disinfect any bags that have come into contact with raw meat juices.

Bags made from recycled plastic can be wiped down with cleaners or disinfecting wipes, while cloth bags can be machine washed. Every so often, I toss mine in with a load of towels rather than dedicate an entire washing load, along with the extra detergent and water, to a few bags.

The impartiality of the study has been called into question by the Natural Resources Defense Council, considering the $30,000 in funding granted by the American Chemistry Council.

The NRDC points out that since bacteria occurs everywhere, the study should not single out reusable bags as a threat to public health.

Gerba, of the University of Arizona, does not advise people to stop using their bags, but reminds shoppers to keep them clean. I agree that consumers should not be discouraged from using their bags but rather be vigilant about preventing cross-contamination. Shoppers can request that meats be wrapped in an extra layer of plastic to avoid leaks.

We come into contact with bacteria throughout our daily routine, which is why hygienic practices, such as hand washing, are so important. The reality is that the chances of a person becoming sick due to bacteria from a reusable grocery bag, are very slim.

However, we do need to be smart when using bags over and over. Wash your cloth bags every so often, and wipe down any plastic-based bags that have been used to carry raw meats to reduce the chances of cross-contamination.

Meridith Byrd is a marine biologist and invites read ers to contact her at meridith.byrd@gmail.com.